Synthesis of Brooker’s Merocyanine and Derivatives: Study of Chromism, and Determination of pKas

Over the summer of 2016, we developed and optimized procedures to synthesize a series of solvatochromatic dyes: MOED, MOEL, MeO-MOED, and MeO-MOEL. These dyes have vibrant colors that change depending on solvent, pH, and temperature. A series of different experiments were developed that demonstrated the various unique color-changing properties of each dye. The results are a series of procedures and tests that can be repeated by college-level students in an organic chemistry laboratory class. The tests are simple and fairly quick in order to be completed in one lab day. These experiments are meant to help the students determine things such as how basic or how acidic the dye is and even predict the identities of unknown substances using what they know about how the dyes change in different solvents and pH ranges. These experiments were tested out earlier this year in the organic lab class at Cornell College with success. We believe that these experiments will be enjoyable for the students since they are very vibrant and fun to conduct and watch, and the procedures are fairly simple.